The sub-assembly of the generic type is a piston with injection cooling, that is to say the piston is cooled by way of the injection with cooling oil from the piston skirt-side end in the direction of the at least one feed opening for cooling oil in the cooling channel. The cooling oil penetrates into the cooling channel and brings about cooling of the piston there in a manner known per se, in particular in the region of the piston head.
On account of the high thermal loading of modern pistons, it is desirable also to cool the underside of the piston crown, what is known as the “dome”. To this end, DE 10 2006 056 011 A1 proposes to provide two injection nozzles for cooling oil, of which one serves to supply the cooling channel with cooling oil and the other serves to cool the underside of the piston crown.